Unlike
elsewhere in the world, the solid bullet plays an important role in African
hunting.Members of the Big Bore
AssociationSouthern Africa, home
to those African hunters that pursue the big, the bad and the ugly, spend as
much time on testing and evaluating solids, as plains game hunters spend on
evaluating softs.

Modern
solids are better than ever before in history and one can probably sit back and
say: ‘Well, that is good enough for me.’That may be so, but unfortunately the African game you hunt with solids
just hate not being killed cleanly the first time round. They often exhibit very
unsocial traits, an appalling sense of humour and extreme vindictiveness once you
have made a hash of killing them cleanly.When
it then suddenly becomes your skin on the line, instead of theirs, you tend to
adopt considerably less complacent expectations from what you are going to throw
at these creatures.

What constitutes failure in a
solid?Failure to kill due to
jacket and core separation, or breaking up, comes to mind.Deformation as well.Deformation
normally constitutes base flattening, bending, or a combination of these two.

The
breaking up of solids have largely been solved through bonded core technology
for jacketed lead core solids, and the introduction of homogenous (monometallic)
brass or copper solids such as the Barnes, Thunderbird and GSCustom designs.

That still
leaves deformation; comprising of flattening of a large portion of the tail end
of the bullet on the one hand, and bending on the other.

The
general statement normally is that the bullet struck (nicked) a bone, deformed
and subsequently tumbled, causing it to veer off course.This is an acceptable explanation when the bullet has bent.Virtually without exception the base is not flattened or
deformed, while the nose shows the point of impact through grazing or
deformation.

When it
comes to base flattening the ‘nick-theory’, as described above, just does
not make sense.Why?Because a bullet that has nicked a bone generally exhibits confirmatory
markings on the ogive, and mostly also nose deformation.In the case of base flattening it is extremely rare to find any signs on
the bullet nose indicating a high-speed crash with an animal's foundations.

The nick
theory explains base deformation by holding that the bullet base gyrates or yaws
around the line of flight and penetration – exposing the rear end of the shank
to the terminal media.Such an
exposed part of the shank then nicks a bone.The impact deforms it by flattening the base area – causing it to
tumble and lose direction.

Let us
take a look at the logic behind this by first looking at a couple of photos of typical
base damaged solids.

What
immediately becomes obvious is the extent of the base deformation, measured both
in bullet length and width.Now
just imagine how skew the bullet must have been at the moment of impact with
the bone, in terms of this theory, to suffer this kind of damage almost from the
middle of the shank. Ask
yourself whether the bullet would have reached the animal if its base had yawed
so much during flight that it exposed that much of the shank during travel.

I am simplifying somewhat because a bullet stabilized for
atmospheric travel is less stable in denser animal tissue and yaws a bit more
terminally than in air, but definitely not the half caliber and more of
deformation required for the nick theory to be valid.

In Sketch
1 we have two scenarios, Scenario A, where the bullet base yaws at an angle of
4° around the line of flight, and Scenario B, where the bullet base is about 20°
off the line of flight.The base
deformation we come across generally looks similar to Scenario B – if not more
pronounced.If the nick theory
offered the correct explanation and if the yaw was minute enough for the bullet
to be reasonably accurate and reach the target where aimed, then surely the
deformation should be similar to Scenario A with more or less straight line
deformation between Ax an Ay.

Sketch
1

What we
find in practice is that the base deformation looks much more like in Scenario
B, with the deformation not linear, but curved as represented by line Bx to
By.If you think about it, the
nick theory does not explain why the line curves to the left (in our sketch) of
the direction of the allegedly applied force.Another phenomenon not explained by the nick theory is why we more often
than not find the base also deformed along the Bq – Bz line, if the
force was linear and applied in a straight line and only between Bx and By
as explained by the nick-theory.

For the
base to also collapse along Bq to Bz, it means that some kind of
force transverse (direction Bq – Bx and Bz – By)to the line of
flight must have been experienced.Think
of a blob of dough falling to the floor.On
the side that touches the floor, let’s call it line Bx – By, the
dough flattens.Not only that
though, it also flattens on the top (call it line Bq – Bz) where it had
not touched anything.This
phenomenon is not explained by the nick theory.All sketches were made to convey the concept with image assistance, not
for the sketches to be a perfect rendition of reality.

You can go
even further and fire solids from a big game rifle and check if the holes in the
paper target exhibit the Sketch 1 Scenario B kind of yaw required for the nick
explanation to hold water.

In terms
of the nick theory, the bullet nose would already have passed the source of
deflection (bone) before deformation commences.Apart from the bullet being gyroscopically disinclined to veer off course
at right angles, the deflecting force is imparted to the rear end of the bullet
in terms of this theory.Despite
the impact on the base, the larger and heavier front section of the bullet will
gyroscopically still tend to pull the base back into line after the impact,
softening deviation at right angles to lower angles of deflection.The point I am trying to make is not that it can never happen the way it
is explained in terms of the nick-theory, but that it would be the exception rather
than the rule.

What
actually happens most of the time is that a bullet is stabilized for atmospheric
travel with a specific rate of twist in the barrel.Let us assume a 500 - grain .458 caliber jacketed solid measuring
1.388” in length.In terms of the
Greenhill formula it requires a twist of 1: 23.5” to be stable in flight.It is not really important for purposes hereof, but the
Greenhill formula normally provides a stability factor in excess of the
theoretical 100%.This is to ensure
that the bullet would be stable across a wide velocity spectrum, even if the
atmospheric conditions are not ideal.

It is not
that simple though.The most
authoritative source for American readers surely remains Hatcher where he writes
on p.557 of Hathcer’s Notebook: ‘… The Greenhill formula gives the
spin necessary to stabilize the flight of the bullet in air; in denser materials
more spin is required.For a bullet
to have stable flight in any material other than air, the spin, as worked out
for air, must be multiplied by the square root of a number found by dividing the
density of the material in question by the density of air.Water has a specific gravity about 900 times that of air, so to be stable
in penetrating water, the bullet would require a twist …… 30 times as great
as that for flight in air.’

If we
assume for convenience of calculation only that animal tissue roughly equals
water’s specific gravity, then the rate of spin of the bullet should be
tightened to 23.5 divided by 30 for a spin of one revolution in 0.783”!The rate of spin of the solid bullet in our example cannot be changed
upon impact and will remain roughly at the air stable 1,149 rps instead of the
34,468 rps required to be similarly stable in water/animal tissue.The instability dramatically increases the bullet’s tendency to tumble.Once the bullet tumbles it exposes its shank and base to the kind of
impact deformation on bone and sudden change of direction commensurate with the
structural damage normally exhibited by base deformed solids.In other words, – the bullet becomes unstable, tumbles (not merely yaws
more) and if it then impacts on bone or something, it deforms and could veer of
course at an acute angle.

Because
the direction of the forces can point anywhere, rather than basically linear
with the line of flight, as claimed by the nick-theory, this ‘tumble-theory’
explains the nature and extent of the base deformation eminently better than the
nick theory.The tumble theory also
better explains the degree and severity of bullet deviation from its original
line of flight than the nick-theory.

Sketch 2

Sketch Two
Scenario C shows the bullet in flight as it enters the terminal medium and
becomes unstable.Scenario D show
the bullet tumbling and impacting on a bone or obstruction.

How can a
solid be designed to counter the unavoidable terminal instability and tendency
to tumble?The first solution lies
outside of the bullet design. Gyroscopic stability of the bullet must be
increased by using a much tighter rate of
twist for dangerous game rifle barrels, given bullet length, than is the norm.

Secondly
– opt for the shortest possible solid of sufficiently good quality and design.A 500-grain brass wadcutter of .458 calibre is shorter than a round nose
of the same weight, material and calibre and that in turn is shorter than such a
spitzer.The late Elmer Keith
introduced us to the improved wound channel and energy transmission properties
of the wadcutter.This is confirmed by Duncan MacPherson in his work Bullet
Penetration – Modelling the Dynamics and Incapacitation Resulting from Wound
Trauma, based on the research of the world’s leading wound ballistics
expert, Dr Martin Fackler.By
opting for this shape one would incorporate as much punch into your solid as
possible.

Although
reasonably compatible with single shot and double rifles, the wadcutter is not
at all compatible with smooth and flawless feeding in bolt action rifles.One step down takes us to the semi-wadcutter that can very
effectively be combined with bolt action rifles.

The
semi-wadcutter with its large flat nose also has other advantageous properties
apart from relative compactness and effective transferring of energy.These additional properties we will now move to, may or may
not, contribute to increased effectivity in a given situation, but the existence
of these properties at least have no detrimental terminal effect.

In terms
of the explanation presented above, the inevitable conclusion is that a solid
should always tumble due to it becoming unstable in terminal media such as
animal tissue – yet they quite often do not.How can that be explained?

First is
the issue of shoulder stabilization, and secondly there is supercavitation.

Shoulder
stabilization occurs when a free stream of moving matter such as water or flesh
hits a plane such as a bullet’s nose, the stream is only stopped at one single
point in the middle of the plane (bullet nose).The point where this occurs is called the stagnation point (SP). All
other stream particles deviate to the side of the plane.Logically the force from the stream develops pressure on the face of the
plane.Graphically this is best
explained by the enclosed diagram (Sketch 3) published in the
1920’s by Ludwig Prandtl.

Sketch 3

The
red lines denote a stream of fluid (meat – animal tissue) impacting on a plane
(wadcutter bullet nose).The red
stream lines denote equivalent speeds of tissue displacement, while the blue
eliptical lines denote equivalent pressure (isobars) that develop on the
wadcutter bullet face during the process of straight line penetration.In the center one finds SP – the stagnation point, at which point the
fluid stream is stopped and where pressure is at it’s highest.

Shoulder
stabilization basically entails that, when an object such as a flat plane
(wadcutter bullet face moving though air, or animal tissue) the medium through
which the bullet moves is deflected equally in all directions. Pressure
dissipates as distances increase from the stagnation point.The pressure naturally is highest at the center (stagnation) point and
when a bullet moves in a straight line, the pressure, called jam pressure,
is evenly distributed across the bullet nose but drops off towards the edges of
the bullet face.

When the
traveling bullet lacks or loses directional stability and tilts in any
direction, the stagnation point (of highest pressure) shifts off center in the
same direction in which the base deviates from straight flight.The point of highest pressure thus shifts towards the leading front edge,
while it drops off towards the trailing edge – resulting in uneven pressure
distribution.Because the highest
pressure is closest to the leading edge, it then retards the leading edge more
than it retards the trailing edge, as the pressure / resistance (retarding
force) on the trailing edge is less.This
redistribution of pressure combats tumbling to some degree as it continuously
attempts to re-align the bullet center along line of travel.This phenomenon is illustrated in Sketch 4.

Sketch 4

Just as shoulder stabilization contributes towards atmospheric stability during flight,
it similarly contributes towards terminal stability during penetration.The rough extent to which shoulder stabilization counters a semi
wadcutter bullet’s tendency to tumble can be calculated by a good physicist
such as the German hunter, Lutz Möller, who has been doing some research in
this regard.How much we do not
know, but it can be modeled by a physicist with the variables at hand.

One must
of course accept that the contribution to stability that can be made by pressure
on the relatively small face of a flat nosed bullet, can never compare to the
forces involved in gyroscopic failure or the leverage that follows tumbling.At worst it possesses higher theoretical tumbling resistance potential
than sharper tipped solids.

The second
explanation is forwarded by Dr Norbert Hansen, designer of the SuperPenetrator
solid.Many of us have seen
supercavitation taking place when watching the propeller of a boat spinning through
water and bubbles form along the leading edges of the propeller blades.

When a
body moves through a fluid at high speed and the fluid has to move around it at
a rapid pace, the pressure in the flow area drops in terms of Bernoulli’s law.In the case of a bullet traveling through a medium such as
water (or animal tissue containing huge percentages of water), the water or
tissue has to flow around the bullet.The
faster the bullet travels through the water, the more the pressure in the flow
decreases and a point can be reached where the flow pressure equals the vapour
pressure of water (or any other medium it is traveling through).When that occurs, the water converts to gas and bubbles or cavities
appear and that constitutes cavitation.The
sharper the edge across which the flow occurs (such as a semi-wadcutter leading
edge), the easier it happens.The
more the cavitation due to faster flow (higher velocities) the more rapid the
extent of cavitation, until a point is reached where all the small vapour
bubbles fuse into a large, stable bubble around the bullet (Sketch 5).The single large bubble enveloping the bullet constitutes
supercavitation.The effect of
which is that only the meplat on the bullet nose remains in contact with the
terminal medium.The rest of the
bullet travels in a capsule of low-pressure tissue vapour, much more comparable
to air than water or flesh.

Sketch 5

While
encapsulated in this low pressure cavity, penetration reducing drag on the
bullet as well as its tendency to tumble is reduced because it travels in a
virtual atmospheric medium – not the 30-40 times denser water or body tissue.Unfortunately this supercavitation bubble is fragile and
easily lost in the rough conditions prevailing when a bullet travels through an
animal.When it is lost, tumbling
follows.

Hansen’s
experimentation (on test media and elephants) is very promising.On wet media and body shots,traditional
round nose solids provided an average of 31.5” of straight line penetration
before tumbling, whereas the flat nose, supercavitating bullets achieved an
average of 95.0” of stable penetration.
This is similar to the reported 78" to 144" penetration reported on
elephant with GS Custom FN solids where supercavitation also occurs. Supercavitation
is therefore another reason for the current African philosophy that a
solid should have a large flat nose (meplat).Not only for maximum shock transfer, but also for increased terminal
stability potential in terms of the supercavitation and shoulder stabilization
concepts.In dry media (bone and
elephant skull) where supercavitation does not play an important role, these
flat nose bullets penetrate less than round nose bullets.However, in all instances homogenous 500-grain .458” semi wadcutter
solids launched at muzzle velocities exceeding 2,200 fps provided satisfactory
penetration in frontal brain shots on elephant.

Seeing
that the design criteria derived from the above not only point to a
semi-wadcutter shape with a sharp intersection between the meplat and ogive, but
at homogenous construction, one can then just as well add a banded shank to the
design to reduce barrel fouling andpressure.

The
two bullet designs currently coming closest to meeting the above criteria, are
the GS Custom Flat Nose Solid (extensive range of weights and calibers)
manufactured in Port Elizabeth, South Africa, and the limited range of
SuperPenetrators manufactured by Michael Reichenberg Spezialgeschosse in
Germany.

GS Custom Bullets,situated in Port Elizabeth on the East Coast of South Africa,
manufactures solid copper, turned, monolithic bullets for hunting and sport shooting. These bullets
are used by hunters on several continents, hunting from the smallest of antelope to the largest
of dangerous game, using the smooth HP bullet, as well as the more popular HV, FN and SP bullets
with the patented drive band concept. GSC bullets are configured for the highest possible ballistic
coefficients. SP bullets are mainly used for sport shooting. All GS Custom Bullets are moly coated.